الفهرس 
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Abstract
Gold nanoparticles (AuNPs) have been considered as an ideal candidate in various biomedical applications due to their ease of tailoring into different size, shape, and decorations with different functionalities. The current study was conducted to investigate (both in vitro and in vivo) some of the genetic and epigenetic alterations in lung cells in response to the exposure to AuNPs. Forty Wister rats were divided into two equal groups, control group and AuNPs-treated group received a single intravenous (IV) injection of citrate-capped spherical AuNPs (25 ± 3 nm) at a final dose of 0.015 mg /kg body wt. Lung samples were then collected from both groups at one day, one week, one month and two months post-injection. The in vitro experiment involves the treatment of human lung fibroblast cells (WI-38) with the same AuNPs sphere at a final concentration of 2 nM for 24, 48, 72 and 96 h. Transmission electron microscopy (TEM) and energy-dispersive X-ray (EDX) spectroscopy verified both the in vivo and in vitro cellular uptake of AuNPs into the cytoplasm at the ultrastructural level. The in vitro effect of AuNPs on cell viability was investigated by MTT assay. The molecular modifications caused by AuNPs exposure at level of expression of microRNA-155 (miR-155) were analyzed by TaqMan® qRT-PCR. Meanwhile, the molecular alterations of two of miR-155 target genes; protein S (PROS1) and tumor protein 53 inducible nuclear protein 1 (TP53INP1) were investigated by qRT-PCR with the determination of the in vivo protein S (PS) expression by western blotting technique Moreover, the alterations of two of DNA damage response (DDR) genes; Breast Cancer Susceptibility 1 (BRCA1) and Nibrin (NBN) genes were measured by qRT-PCR. The present study suggests that AuNPs could induce genetic modulations in lung cells both in vivo and in vitro experimental models which assort further insights into AuNPs molecular mechanisms and their impact on epigenetic processes that can predispose to lung injury.